Bulk-storage receptacle with helical chute

ABSTRACT

A bulk-storage bin having a cylindrical wall is provided thereon with a helical chute having an inlet portion at its upper end whereby the bulk material is introduced into the bin and descends along the helical chute to be spread uniformly in the interior of the bin. The helical chute is provided as an inwardly open channel whose floor is a ramp which is inclined radially. According to the invention, in the transition region between the inlet and the remainder of the helical chute, the tangential inclination forms a continuous transition to the tangential inclination of the helical chute while the radial inclination in the transition region is always sufficient to permit the bulk material to slide along the ramp by gravitational force. This inclination thus is such that the total slope of the ramp is greater than the critical sliding angle (frictional re-ardation) of the piled material.

FIELD OF THE INVENTION

The present invention relates to bulk-storage bins, bunkers and silosand, more particularly, to improvements in bulk-storage systems whichhave a helical or spiral chute along an inwardly facing or outwardlyfacing wall defining the storage chamber to distribute the bulk materialin the bin and/or to facilitate the complete discharge of such materialupon emptying of the bin.

BACKGROUND OF THE INVENTION

Bulk-storage bins, bunkers or silos, usually for flowable particulate,granular and like solids, can be provided with inwardly open helical orspiral chutes or ramps along an inner wall (or outwardly open chutealong an outwardly facing wall) defining a bulk-storage compartment. Thelatter can be used in subterranean operations and is filled from thetop. The mined or other particulate or broken mineral matter can beintroduced at the upper end of the storage container by an inlet to theaforementioned chute and can be distributed thereby with the interior ofthis container.

Thus the chutes serve to discharge the bulk material introduced in theupper end of the chute more uniformly over the internal cross section ofthe bulk-storage container than systems which merely dump the solidsinto the bin from the upper end or top of the latter.

The chute, which is generally an inwardly open channel attached to orformed in the wall of the chamber, also facilitates total emptying ofthe bin.

The chute has the configuration of a screw thread, i.e. helix, which isinclined downwardly and can extend over the entire height of the bin ina plurality of turns. The chute thus has a tangential inclination suchthat, under the effect of gravity, the bulk material descends the chuteso that its downward movement and momentum produces a centrifugal forcewhich urges the material outwardly against the wall of the bin so thatthe chute can be opened inwardly, i.e. there is no need to fully enclosethe path of the material along the chute.

In general, the chute has, in addition to this wall against which thematerial is urged by centrifugal force, a ramp supporting the weight ofthe material against the vertical component of the gravitationalinfluence. This ramp, which lies transverse to the vertical bin wall, isusually inclined downwardly and inwardly (hereinafter referred to as a"radial inclination") so that, in section in a vertical axial plane ofthe bin, the surface of this ramp is inclined to the horizontal. Thecombination of this tangential inclination and the radial inclination atany point or region of the helical chute gives rise to a "slope" or"gradient" of the ramp from the vertical wall of the bin to the freeedge of the ramp lying inwardly of the wall. This slope or gradient isselected such that, upon emptying of the bin, any bulk material restingon the ramp will slide freely downwardly and hence accumulations of bulkmaterial on the ramp are precluded. The slope is thus sufficient topermit the bulk material resting with zero momentum and solely itsstatic inertia to begin to slide downwardly.

The bulk material is supplied to the helical chute by an inlet devicewhich can include a laterally closed and either helical or straightinlet duct or chute. The inlet chute has its supporting wall or inletramp designed with zero radical inclination, i.e. in a vertical planethrough this supporting wall, the wall is parallel to the horizontal andincludes zero angle therewith.

Between this inlet chute and the helical chute, therefore, there is atransition region in which the horizontal ramp of the inlet chute mergeswith the radially inclined ramp of the helical chute. In this transitionregion, the radial inclination of the ramp continuously increases fromzero (at its junction with the inlet chute) to the radial inclination ofthe helical chute at its junction therewith.

The bulk material introduced through the inlet chute and passed on tothe helical chute is acceleration by its momentum at a rate determinedby the tangential inclination. The acceleration becomes zero, i.e. thebulk material reaches a constant velocity, when the velocity-dependentcomponent friction upon the bulk material is equal to the downwardlyeffective gravitational component along the helical chute.

The conventional bulk-material storage bins of the afore described type,the tangential inclination is constant over the entire length of thehelical chute although the tangential inclination can be somewhatgreater at the inlet chute. However, since the radial inclination of thetransit region is practically zero at the start of this region,experience has shown that bulk material which accumulates in a staticcondition on the ramp surface is not discharged when the bin is emptied.To avoid this problem, the bin is filled only up to the top of thehelical chute and the space above the helical chute, i.e. at the levelof the transition region, remains empty. Consequently, a substantialportion of the storage bin remains unused and unusable in theconventional systems, thereby reducing the effective storage capacity ofthe unit.

While it might be suggested that one solution would be to increase thetangential inclination sufficiently to overcome this tendency of solidmaterial to accumulate on the ramp surface of the transition region,this has not been found to be successful in practice because itdetrimentally effects the velocity of the bulk material introduced tothe chute and the movements of the material therealong.

OBJECTS OF THE INVENTION

It is the principal object of the present invention to provide animproved bulk-material storage bunker which obviates the aforedescribeddisadvantages.

More specifically, it is an object of the invention to provide a storagereceptacle for bulk material having a helical chute in which the problemof nondischarge of portions of the stored material are eliminated.

It is also an object of the invention to provide an improved bin for thestorage of flowable bulk solids whereby the capacity of the receptaclecan be increased or the receptacle can have an optimum capacity.

SUMMARY OF THE INVENTION

These objects and others which will become apparent hereinafter areattained, in accordance with the present invention, in a storagereceptacle of the type described herein, in the transition region, thetangential inclination of the ramp continuously increases from the inletchute to the helical chute and, over the entire length of thistransition region, the gradient or slope of the ramp is greater than thecritical friction angle of the bulk material to be stored in the bin.The term "critical friction angle" is the angle to the horizontal atwhich the material, originally in a static state, begins to slide downan incline. It may be determined by piling the material on a horizontalsurface having the same surface characteristics as the ramp, i.e.composed of the same material as the ramp, and then inclining thesurface gradient to the horizontal until the mass slides freely from thesurface. At the angle included between this surface and the horizontalat which the entire mass slides freely from the surface, a measurementcan be made and will correspond to the critical angle described above.

Thus the critical angle over the entire length of the transition regionbetween the peripherally closed inlet chute and the inwardly openhelical chute is such that none of the bulk material can remain on theramp upon emptying of the bin.

This relationship means, moreover, that from the inlet chute to thehelical chute, the radial inclination of the ramp progressivelyincreases to correspond to the progressive decrease in the tangentialinclination over the length of the transition region, the slope orgradient being a composite of these two inclinations. This insures thatthe slope will have a value preventing static accumulation of the solidthereon over the entire length of the transition region in spite of thefact that the radical inclination is negligible immediately adjacent theinlet chute.

Naturally, the critical angle is dependent upon the particular bulkmaterial stored and the characteristics of the surface, both of whichdetermine the frictonal relationships.

In the transition from the straight chute portion of a chute to thecurved portion of a helical chute, especially when there is asimultaneous change in the tangential inclination, there ariseoscillating movements of the bulk material which can bring about anonuniform and rapid wear of the surfaces of the ramp or chute. This canbe avoided, in accordance with a feature of the invention, by formingthe inlet chute also with a helical or spiral curvature. This ensures acontinuous increase in the centrifugal force applied to the bulkmaterial so that the latter is held substantially uniformly against thewall of the chute and ensures a uniform increase in velocity until theaccumulation is reduced to zero. This has also been found to protect thegrains of the material stored.

One of the advantages of the system of the present invention is that itpermits the storage bin to be filled to the upper end of the transitionregion. It is possible, therefore, to provide the inlet chute above thetop of bin and in conjunction with a conveyor belt which can carry thebulk material to the opening of the inlet chute spaced above the top ofthe bin. The discharge end of the conveyor, at which the bulk materialis flung from the belt, can then be juxtaposed with this mouth wellabove the top of the bin. The upper end of the transition region andhence the lower end of the inlet chute can thus lie in the horizontalplane of the top of the bin. This has been found to insure completeutilization of the bunker capacity. It is another advantage of thepresent invention that there are no limitations to the height within thebin to which the bulk material can be stored. There are, of course, noaccumulations of bulk material within the bin upon emptying or dischargethereof. The system has been found to permit of increased filling speedwith optimum ultilization of the cross section of the bin and hence tobe effective for wide or large-cross section bins with uniformdistribution of the material over the entire cross section. Furthermore,the wear of the ramp or chutes is held to a minimum.

Most surprisingly, the system also eliminates oscillations within theflow of the bulk material along the transition region and on the helicalchute.

BRIEF DESCRIPTION OF THE DRAWING

The above and other objects, features and advantages of the presentinvention will become more readily apparent from the followingdescription, reference being made to the accompanying drawings in which:

FIG. 1 is a vertical section through a portion of a bulk-storage binaccording to the present invention having a helical chute;

FIG. 2 is a developed view of a helical chute and associated inletchute;

FIG. 2A is a section taken along the line IIA--IIA of FIG. 2 through theinlet chute;

FIG. 2B is a section taken along the line IIB--IIB through an upperportion of the transition region;

FIG. 2C is a section taken along the line IIC--IIC through anintermediate region of the transition zone, in FIG. 2;

FIG. 2D is a section along the line IID--IID of FIG. 2 at the upper endof the helical chute of FIG. 2;

FIG. 3 is a view similar to FIG. 1 and taken along the line III--III ofFIG. 4 illustrating an embodiment of the invention provided withintermediate storage for the bulk material;

FIG. 4 is a plan view from above of the storage facility of FIG. 3;

FIG. 5 is a detail cross-sectional view in an axial plane of a storagebin having a cantilevered ramp;

FIG. 6 is a partial perspective view and cross section illustrating thelining of the interior of the bin and the chute with panels according toa feature of the invention;

FIG. 7 is a detail view of the region VII of FIG. 6; and

FIG. 8 is a perspective section of an arrangement in which the bin wallis assembled from blocks and the ramp is cantilevered thereon.

SPECIFIC DESCRIPTION

The storage facility illustrated somewhat diagramatically in FIG. 1comprises a bin 1 which can be located beneath the ground and can befilled with the bulk material through an inlet chute 3, the bulkmaterial passing along the helical chute 2. A transition region 4 isprovided between the helical chute 2 and the inlet chute 3.

The bin 1 can be composed of concrete poured in place, bricks or cementblocks, the latter being preferred, and has the chute 2 and thetransition region 4 formed unitarily therein. In the embodimentillustrated, the chute 2 conforms to an outer helix. In this case it isopen inwardly to the storage chamber 1a for the bulk material in thebin 1. Naturally, such a chute can also be provided as an inner helixwhen, for example, the chute is disposed centrally in the chamber 1a.

The helical chute 2 and the transition region 4 lie along the curves ofthe helix, i.e. are helically curved to ensure an acceleration of thematerial from the mouth 3a of the chute 3 which is located above the top8 of the bin 1, to the chute 2 located below the mouth and over theentire transition region 4, thereby ensuring a continuous increase inthe velocity of the bulk material until it reaches the maximum speedwith which it travels along the helical chute 2.

The contours of the helical chute 2 and the inlet arrangement 3, 4, willbe more readily apparent from FIG. 2 and the cross-sectional views ofFIGS. 2A-2D.

The helical chute 2 comprises a channel 5 which is open toward theinterior 1a of the bin 1 and is provided with a ramp or channel base 6which lies transversely to the bin wall 6a forming the bottom of thechannel. The ramp 6 defines a radial inclination γ with the horizontalas is best seen in FIG. 2D. The section of FIG. 2D thus is a verticalsection taken in an axial plane of the bin and the angle γ is formedbetween the ramp 6 and the horizontal.

The corresponding ramp angle, measured between the surface 3a of theperipherally closed inlet chute 3 and the horizontal is, of course,zero. In the transition region, the ramp 6 has a progressivelyincreasing radial inclination from zero adjacent the inlet chute 3 tothe maximum value γ at the helical chute 2 as can be seen by comparingFIGS. 2B and 2C.

The helical chute extends downwardly with a tangential inclination α₁while the inlet chute 3 terminates with a tangential angle α_(o) whichis greater than the tangential angle α₁. Between the inlet chute 3 andthe helical chute 2, therefore, the inclination of the transition regionprogressively diminishes and, as indicated, can have an intermediatevalue α.

The bulk material introduced at the inlet chute 3 flows, as a result ofthe gravitational effect, with progressively increasing speed along theramp 6 in the transition region and is urged by centrifugal forceagainst the wall 6a as a comparison of FIGS. 2B, 2C and 2D willdemonstrate. It is important, from the viewpoint of the presentinvention, that over its entire length between the bottom of the inletchute 3 and the top of the helical chute 2, the slope of the ramp 6exceed the critical friction angle for static material on this ring. Thetangential inclination α_(o) of the inlet chute and the tangentialinclination α over the entire length of the transition region 4 can begreater than the tangential inclination α₁ of the helical chute 2 with acontinuous decrease in the tangential angle as indicated. The tangentialangle α_(o) over the length of the inlet chute 3 can be constant.Because the slope or gradient over the entire length over the transitionregion of the ramp 6 exceeds the critical friction angle, upon emptyingof the bin, bulk material cannot be retained on the chutes to block thelatter.

In the embodiment of FIGS. 1, 2 and 2A-2D, the mouth 3a of the inletchute lies above the top 8 of the bin 1, i.e., above the opening of thisbin. This can be done without difficulty by providing a conveyor whosedischarge end casts the bulk material into the mouth 3a of the inletchute 3 and lifts the material to this level (see FIG. 3). Thisarrangement of the inlet chute 3 permits the bin to be filled to theplane illustrated at H which can be grade level. The full bin capacityis thus exploited without the difficulty that bulk material may remainin the chutes, such bulk material flowing freely by gravity even out ofthe transition region of the chute.

As can be seen from FIGS. 3 and 4, the inlet device can include anintermediate storage hopper 9 which can be disposed above the mouth ofthe inlet chute 3', here extending somewhat beneath the top 8' of thebin 1'. The hopper 9 is provided with a level sensor 10 which respondsto the height of the material in the hopper and operates a closure 11.This permits a substantially continuous and uniform supply of the bulkmaterial to the chutes described previously and further avoidsoscillation of the stream of bulk material 7 on the chute.

In FIG. 5 I have shown a particularly advantageous construction of thestorage bin or silo, according to the invention, especially intended toprovide a bin wall 1 and a ramp 12, performing the function of the ramp6, previously described, which is extreme-16 reliable and has a longuseful life. The ramp and hence the chute of which the ramp is a part isformed from a plurality of helical ramp sections 12 disposed inend-to-end relationship and secured, e.g. by bolts 13, to the bin wall.Each of the sections 12 can comprise a wear-resistant layer or plate 15of L-section disposed on a concrete body 16 composed of reinforcedconcrete and anchored to the wall of the bin 1 by the bolts 13 via anadhesive layer 14 of synthetic-resin mortar. Preferably the layer 14 isapplied before the sections are mounted in place to the prefabricatedsections. The wear-resistant layers 15 can consist of artificial basaltor synthetic resin. This results in a certain oscillation damping effectfor the combination of materials which is especially effective. Theprefabricated sections 12 can have widened flanges 17 which can carrypins or recesses for connection at the junctions 18 in a manner whichhas not been illustrated.

The arrangement illustrated in FIG. 5 can be readily assembled from theprefabricated chute sections 12 by lowering them into the silo or bin 1and then bolting and cementing them to the inner wall thereof. Thebolting can be effected with prestressing. The bonding of the sectionsto the wall can be effected by, for example, first bolting the sectionto the wall with clearance and then introducing the synthetic-resinmortar or other vibration-damping adhesive mass, adapted to form theadhesive layer 14, as a grout between the wall of the bin 1 and theouter surface of the sections, e.g. by pouring the mass into a gapbetween the sections and the wall and permitting the adhesive materialto harden in place. In this case, the adhesive layer 14 need not beprovided upon each section 12 before it is positioned within the bin noris it necessary to provide the adhesive layer previously on the wall.Naturally, either the bin wall or the section can have a thin adhesivelayer which is supplemented by grouting in the manner stated.

The sections 12 can be constituted from a fiber-reinforced binder suchas cement or a polymer-impregnated concrete. The fibers can bepolypropylene, polyamide, carbon (e.g. graphite fibers) fiber glass andpreferably are alkali-resistant fiber glass or steel. The polymer forimpregnating the concrete is preferably polymethylmethacrylate.

According to a feature of the invention, a firm bond is provided betweenthe juxtaposed surfaces of the bin and the chute or ramp sections 12 bythe aforementioned adhesive. The advantage of this arrangement is thatthe adhesive layer 14 between the wall of the silo 1 and the juxtaposedwall of the sections 12 forming the chute 2 reduces vibrations whichhave heretofore been found to damage the chute. These vibrations mayarise from oscillating movements of the flowable bulk materialtraversing the chute at high speed. In addition, the adhesive provides afirm anchorage to the bin wall and prevents loosening of the boltarrangement. At the joints 18 between the sections 12, the latter mayalso be adhesively bonded together and preferably are also secured bystraps disposed on the rear or underside of the sections and, ifdesired, along the flanges 17. The arrangement excludes overloading ofthe chute by the bulk material to be stored in the bin.

FIGS. 6 and 7 illustrate an embodiment in which the bin 1 and its chuteare covered internally by panels 19 which can be provided in animbricated pattern. Each of the panels 19 is provided along the sidefacing the concrete mass of the silo with an elastic inner layer 20adapted to cushion vibration and a wear-resistant outer layer 21defining the storage chamber. The panels 19 may each be constituted as asegment of cylinder surface and preferably have rectangular projectionson a plane parallel to the axis of the cylinder. They can form thesmooth surface of the cylindrical wall as well as the helical chute.

At their rear sides, each panel is provided with anchor rods 22 whichcan be embedded in the concrete of the silo and form the anchoring meansfor the panels together with rearwardly extending flanges or ribs 23which adjoin at the contiguous panels as can be seen in FIG. 7. Theelastic inner layers 20 can be coated with an adhesive bonding layer,for example, of synthetic-resin mortar.

Advantageously, the elastic inner layers 20 are constituted ofreinforced concrete or fiber glass-reinforced synthetic resin. Thewear-resistant layers 21 can be composed of hard concrete, modifiedsynthetic resins which can contain inlays of hard material or the like.The result is a highly effective oscillation damping lining for the siloor bin which can withstand the stresses to which the bin is normallysubject.

The panels can be composed of a fiber-reinforced binder such as cementor polymer-impregnated concrete, the fibers and impregnated polymerhaving the compositions set forth previously.

The construction of the bulk material receptacles of FIGS. 1-4 withlinings of panels as described in connection with FIGS. 6 and 7 isrelatively simple. An outer shell is first provided, e.g. of concrete,masonry or the like and an inner shell is ten assembled from the panels19. The space between the outer shell and the inner shell is then filledwith concrete which is cast in place, the space having previously beenprovided with the usual concrete reinforcements 24 of steel. Naturally,similar panels can be used to form the outer shell and can remain inplace after the concrete is poured. The panels thus not only form thelining of the wall of the chamber in which the bulk material is storedbut also serve as forms for the casting of the support structure of thesilo.

In FIG. 8 I have shown an arrangement in which the bulk-material bin isprovided with the helical chute 2 and is formed from blocks 25 and 26,the blocks 25 being cylindrical segments while the blocks 26 haveramp-forming sections 27 cantilevered thereon. The blocks 26 thus have aT-shape or profile with the leg of the T forming the chute. The sections25 as well as the sections 26 have rectangular projections in axialplanes of the bin.

The chute forming projections 27 and the adjoining wall of each of thesections 26 can be formed as prefabricated reinforced concrete bodies ina single piece with a rear-resisting layer 15 of artificial basalt orsynthetic resin as previously described. Connectors 29, e.g. keys, boltsor plug- and socket arrangement, fixing the blocks 25, 26 contiguouslytogether at their junctions 28.

A bin formed from the blocks 25 and 26, with or without thechute-forming portions 27 can be rapidly and simply erected tosubstantially any height in a subterranean bore or shaft of suitablediameter. The blocks can be used to line the wall of the bore andsimultaneously form the wall of the bin grouting 30 being thereupon castbehind the blocks or between the blocks and the wall of the shaft orbore. The grouting 30 can be constituted of mortar, especiallysynthetic-resin mortar, which can be forced under pressure into thespace behind the blocks. The block walls can be prestressed by windinghorizontal or helical cable arrangements around the cylindricalstructure formed from the blocks, applying tensioning rings therearoundor by passing reinforcing cables or rings through aligned openings inadjoining blocks and stressing them to apply a radially inward prestressor peripheral compression to the assembly. The blocks 25, 26 can beconstituted of fiber-reinforced binder such as cement orpolymer-impregnated concrete as described.

I claim:
 1. A bulk-storage receptacle comprising:a structure formed withan upright wall defining a storage chamber for flowable bulk material;means forming a helical chute opening toward said chamber and spiralingdownwardly along said wall, said helical chute having a ramp receivingsaid material and extending generally transversely to said wall whilebeing formed with a first tangential inclination and a first radialinclination; a peripherally closed inlet chute disposed above saidhelical chute for feeding bulk material to said helical chute; and atransition region between said inlet chute and said helical chuteprovided with a ramp delivering said bulk material to said inlet chute,the ramp of said transition region having a tangential angle varyingcontinuously from a second tangential inclination adjacent said inletchute to said first tangential inclination at said helical chute; saidramp of said transition region merging into said ramp of said helicalchute and having over the entire length of said transition region aslope greater than the critical friction angle for said material.
 2. Thebulk-storage receptacle as defined in claim 1 wherein said inlet chuteis helically curved.
 3. The bulk-storage receptacle as defined in claim1 wherein said inlet chute has a constant tangential inclination equalto said second tangential inclination.
 4. The bulk-storage receptacledefined in claim 1 wherein said structure has an open upper end and saidinlet chute is disposed above said upper end.
 5. The bulk-storagereceptacle defined in claim 1, further comprising a storage hopper on anupper end of said inlet chute, control means between said hopper andsaid inlet chute for metering said material into said inlet chute, andlevel-responsive means in said hopper for monitoring the level ofmaterial therein to operate said control means.
 6. The bulk-storagereceptacle defined in claim 1, further comprising oscillation-dampingadhesive means bonding said chute to said wall.
 7. The bulk-storagereceptacle defined in claim 6 wherein said bonding means is an adhesivelayer of synthetic-resin mortar.
 8. The bulk-storage receptacle definedin claim 1 wherein said chute is formed in aligned sections and isbonded to said wall with synthetic-resin mortar.
 9. The bulk-storagereceptacle defined in claim 1 wherein said ramp is formed with awear-resistant layer of a material selected from the group whichconsists of artificial basalt, steel and synthetic resin.
 10. Thebulk-storage receptacle defined in claim 1 wherein said ramp is formedin sections and mounted on said wall, each of said section beingcomposed of reinforced concrete or a fiber-reinforced binder orpolymer-impregnated concrete.
 11. The bulk-storage receptacle defined inclaim 10 wherein the reinforcing fiber is selected from the group whichconsists of polypropylene fiber, polyamide fiber, carbon fiber, fiberglass and steel fiber.
 12. The bulk-storage receptacle defined in claim10 wherein the impregnated polymer is polymethylmethacrylate.
 13. Thebulk-storage receptacle defined in claim 1 wherein said wall and saidchute are constituted of panels mounted in mutually contiguousrelationship, each of said panels having an elastic inner layer and awear-resistant outer layer adapted to define the chambers for receivingsaid material.
 14. The bulk-storage receptacle defined in claim 13,further comprising an adhesive layer applied to said elastic innerlayer.
 15. The bulk-storage receptacle defined in claim 13 wherein saidelastic inner layer is composed of reinforced concrete or fiber glassreinforced synthetic resin.
 16. The bulk-storage receptacle defined inclaim 13 wherein said wear-resistant outer layer is composed of hardconcrete synthetic resin having a hard material inlay or artificialbasalt.
 17. The bulk-storage receptacle defined in claim 14 wherein saidadhesive layer is a synthetic-resin mortar.
 18. The bulk-storagereceptacle defined in claim 13 wherein said panels are composed at leastin part of fiber-reinforced binder or a polymer-impregnated concrete.19. The bulk-storage receptacle defined in claim 18 wherein thereinforcing fibers are selected from the group which consists ofpolypropylene fiber, polyamide fiber, carbon fiber, fiber glass andsteel fiber.
 20. The bulk-storage receptacle defined in claim 18 whereinthe impregnating polymer is polymethylmethacrylate.
 21. The bulk-storagereceptacle defined in claim 1 wherein said wall and said chute areformed from cylindrical-segment blocks, further comprising means forsecuring said blocks in mutually contiguous impregnated relationship,the blocks forming said chute having a T-profile.
 22. The bulk-storagereceptacle defined in claim 21 wherein the blocks defining said chuteare formed unitarily with a wall portion and a chute portioncantilevered on said wall portion, said portions being lined with awear-resistant layer.
 23. The bulk-storage receptacle defined in claim21, further comprising prestressing means extending around said blocks.24. The bulk-storage receptacle defined in claim 21 wherein said blocksare formed of reinforced concrete, a fiber-reinforced binder or apolymer-impregnated concrete.
 25. The bulk-storage receptacle defined inclaim 24 wherein the reinforcing fiber is selected from the group whichconsists of polypropylene fiber, polyamide fiber, carbon fiber, fiberglass and steel fiber.
 26. The bulk-storage receptacle defined in claim24 wherein the impregnating polymer is polymethylmethacrylate.